# How do you simplify and find the excluded value of (t^2-25)/(t^2+t-20)?

May 15, 2016

Factor both the numerator and the denominator.

#### Explanation:

$= \frac{\left(t + 5\right) \left(t - 5\right)}{\left(t + 5\right) \left(t - 4\right)}$

$= \frac{\left(\cancel{t + 5}\right) \left(t - 5\right)}{\left(\cancel{t + 5}\right) \left(t - 4\right)}$

$= \frac{t - 5}{t - 4}$

To find the excluded value, we must set the denominator to 0.

$t - 4 = 0$

$t = 4$

Therefore, we can state that $t \ne 4$.

Hopefully this helps!